Garbage cleaner for IPFS pinner

[noslav]

Files get cleaned beyond 2 week period locally for rudder -

download would typically happen from local ipfs store (and so is immediate). I plan to add a GC feature which cleans data beyond last 2 weeks. In cases where we might need to download from remote nodes, I've seen files take as much as 10 minutes in downloading.
So for our purposes, where we're immediately working on the items, we expect download to happen immediately since there's no network cost.